New results indicate that the selective serotonin reuptake inhibitor, paroxetine,
can effectively treat depression in patients with Parkinson's disease without
aggravating motor symptoms.

While selective serotonin reuptake inhibitors (SSRIs) have been used to manage
depression in patients with Parkinson's disease (PD), it has not been definitely
determined whether these agents worsen motor symptoms.

The findings are from a study that included 33 non-demented, depressed PD
patients. The diagnosis of depression was new in all patients except for six,
who were receiving low-dose tricyclics at the time of referral.

In order to minimize the potential rebound effect on motor symptomatology in
relation to the anticholinergic properties of tricyclics, patients who had been
taking tricyclics were tapered off the drugs at least three months before
starting paroxetine.

Paroxetine was added in an unblinded manner, starting with 5 mg a day increased
gradually up to 20 mg a day.

One patient showed marked worsening of tremor after treatment. The authors
emphasize that this effect may have occurred as a result of an additive
tremor-inducing effect of paroxetine, since tremor is a common side effect of
this medication. Notably, the increase in tremor in this patient was fully
reversible when paroxetine was withdrawn.

Depression, as evaluated by the Beck Depression Inventory and Hamilton
Depression Rating Scale, improved from baseline to the final visit.

The investigators emphasize that their study had an open-label design and
further noted that the placebo effect in antidepressant studies can be large.
They add that a controlled clinical trial is needed in a larger patient
population to establish the efficacy of SSRIs and their effect on motor function
in depressed PD patients.